Raised garden beds can be great alternatives to planting directly into the ground for a number of reasons. Perimeters of your lawn are often already filled with trees and perennials. Plus they may be in the shade, or lack space for what you want to grow. A raised bed allows you to control what kind of soil you work with, keeping it weed-free, and giving you a chance to make a prime growing substrate full of organic material, with enough space for plants to grow deep roots.
